Neuron-specific expression and physiological regulation of bovine vasopressin transgenes in mice

We have used transgenic mice to analyse the regulation of the bovine vasopressin (BVP) gene. We find that the restriction of BVP gene expression to anatomically and functionally distinct hypothalamic neuronal groups is achieved, in part, by selective repression. The expression of a 1.25 kb BVP proximal promoter, which on its own confers general expression of a reporter to most peripheral and brain tissues, was limited by sequences in the BVP structural gene to neural cells in the adrenal medulla and brain. Transgene expression in the hypothalamus was shown to be regulated by the physiological stimulus of dehydration in parallel with the endogenous gene. The expression of a larger 13.4 kb BVP transgene, containing 9 kb of 5' upstream sequence, the VP structural gene and 1.5 kb 3' of the transcription unit, was even more restricted and resembles that of the endogenous mouse gene. Hypothalamic expression of the 13.4 kb BVP transgene was regulated appropriately in response to an osmotic challenge.